Want to be an expert in anything? Set a schedule and practice at least 10,000 hours.

Psychologist K. Anders Ericsson visited Berlin’s Academy of Music in the early 1990s. He asked every violinist the same question: How many hours have you practiced since you first picked up the instrument?

Generally, everyone at the academy started playing at the same young age, but by the age of eight and onward, the best players put in more hours and the least successful players practiced the least. The best violinists didn’t just practice more than the others; they practiced a lot more — easily attaining 10,000 hours of practice by the age of 20. Conducting the same study with pianists, Mr. Ericsson reached the same conclusion. Surprisingly, he found no “naturals.” No one achieves greatness without putting in long hours. Nor were there any “grinds” who work harder than most, but still struggle in mediocrity. According to Malcolm Gladwell, researchers have settled upon a “magic number” for success in generally any field: 10,000 hours.

How and why someone finds 10,000 hours to practice is the subject of Mr. Gladwell’s new book “Outliers: The Story of Success.” Take Bill Joy, cofounder of Sun Microsystems, the “Edison of the Internet” as some Silicon Valley insiders call him. In 1971, he arrived at the University of Michigan intending to study engineering or math. It was the same year the university’s state of the art computer center opened. Mr. Joy got involved his freshman year and found his passion.

Michigan’s computers were so advanced they cut out a lot of tedious tasks that most old computer required of their users. Mr. Joy told Mr. Gladwell, “It’s the difference between playing chess by mail and speed chess.” Mr. Joy worked on coding, night after night, sometimes until two or three in the morning. Mr. Gladwell writes, “Just look at the stream of opportunities that came Bill Joy’s way. … Bill Joy was brilliant. He wanted to learn. That was a big part of it. But before he could become an expert, someone had to give him the opportunity to learn how to be an expert.”

Bill Joy is an outlier. His success appears to lie outside normal experiences. But this book attempts to show “outliers” are oftentimes the product of conventional circumstances. Mr. Gladwell is famous for his masterful nonfiction storytelling, and in that respect, “Outliers” doesn’t disappoint.

However, just like his previous books, “The Tipping Point” and “Blink,” Mr. Gladwell casts too wide a net with his conclusion. Instead of focusing on the idea of “10,000 hours” as an essential path to excellence, he dampens this theory with determinist conclusions about the role of chance. “We do owe something to parentage and patronage. The people who stand before kings may look like they did it all by themselves. But in fact they are invariably the beneficiaries of hidden advantages and extraordinary opportunities and cultural legacies that allow them to learn and work hard and make sense of the world in ways others cannot. It makes a difference where and when we grew up,” he writes.

The opportunity to fly through 10,000 hours wasn’t simply given to Bill Joy. He made the choice to pursue computer science and it turned out to be a hugely profitable one. Perhaps there was something in the air — the kind of intuitive cultural knowledge Mr. Gladwell himself likes to write about — that influenced Mr. Joy’s decision to go to Michigan and enter the computer science department. If he had gone to another school and studied another subject, maybe Bill Joy would be just as successful and an “outlier” in another way.

Still, Mr. Gladwell provides several examples of research that make the book a must-read for educators, recruiters and parents. A stunning example is his chapter on how poverty and inattentive parenting can stunt opportunities for even for the world’s brightest children.

Mr. Gladwell writes about Chris Langan, who isn’t a success like the other people Mr. Gladwell profiles. But Mr. Langan has a literally off-the-charts IQ — in the 200 range — too high to be accurately measured (Einstein’s IQ was estimated at 150.) Mr. Langan had a troubled family life and grew up in poverty. When he left home, the success that might have come naturally to a man of his intellect never materialized. Trivial circumstances (his mother failed to sign a piece of paper to renew his college scholarship) had dire consequences (Mr. Langan lost his scholarship and left school.) One door slammed in Mr. Langan’s face after another, until he decided to give up on his academic dreams. He took a job as a bar bouncer.

Mr. Gladwell pairs the example of Mr. Langan with a summary of the life of Robert Oppenheimer, who developed the nuclear bomb. Oppenheimer, a man of Mr. Langan’s curiosity and intellect, actually tried to poison his tutor at university. But, he was charming. He could talk his way out of anything, “That particular skill that allows you to talk your way out of a murder rap … is what psychologist Robert Sternberg calls ‘practical intelligence,’” Mr. Gladwell writes.

“Practical intelligence,” the savvy to know what to say to whom, doesn’t come easily to poorer children, as Mr. Gladwell explains drawing from some research in sociology. Children who grow up in poverty are more submissive when addressing adults and authority figures. They aren’t raised to assert themselves. This disadvantage can result in a lifelong struggle with interpersonal communications.

It’s a flawed argument to make, as numerous unexamined factors propelled Oppenheimer to success just as countless reasons contributed to Mr. Langan’s unjust failures, but Mr. Gladwell’s message is clear. Underneath the surface of success or failure are less obvious social situations.

No man is an island. Sheer luck and determination. Mr. Gladwell’s argument that the “self-made man” is a myth is already conventional wisdom. But his hodgepodge of examples add complexity to what might be a cliched thesis. For instance, the Chinese language has words for numbers that are quicker to say than the English equivalency. Given seven digits to memorize, about half of all native English speakers will remember the sequence, while nearly all Chinese speakers will remember it perfectly. “We store digits in a memory loop that runs for about two seconds. We most easily memorize whatever we can say or read within that two-second span. … Unlike English, [the Chinese language] allows them to fit all those numbers into two seconds.” The language is also regular in the words for numbers: Eleven is “ten-one,” 12 is “ten-two.” This bonus, coupled with the culture’s long history of prizing hard work; are thought to by why the Chinese typically have superior math skills.

At his best, Mr. Gladwell discusses solvable problems. He defends University of Michigan Law School’s affirmative action program since the minority students, who might enter the class with lower grades, were found to achieve just as much success later in life as the white students. He suggests Canadian youth hockey leagues divide teams by January through April in one class, May through August in another, and September through December in a third. This is to correct the current data that shows adult all-star players overwhelmingly tend to be born in the early part of the year. As children, physically more mature near-January birth players compete against those with birthdays near-December, due to cutoff dates in annual league enrollment. The older players are encouraged from a young age, while those with birthdays later in the year assume they just aren’t good at hockey.

Of course, not every all-star Canadian hockey player was born before Easter and excellent mathematicians come from all countries. Mr. Gladwell carefully avoids mentioning outliers to his “outliers,” making the book at times, frustrating to read. In spite of these flaws, “Outliers” is evidence of Mr. Gladwell’s 10,000 hours.